The present invention relates to guidance systems and in particular to such systems using changeable signs to lead a person to a predefined target.
Many human activities involve the need to reach a predefined location or object. Guidance means for choosing a preferred route or for identifying the target location or object are in common use, usually in the form of signs. Such signs, clearly visible from a fair distance, allow a person to choose the route to the target without interrupting the travel or risking travel safety. However, when the number of possible routes or targets is large, the use of common signs becomes impractical, because too much visual information must be displayed and then read and interpreted during travel. A changeable sign system capable of providing selectively guidance signals relating to a specific route or target of an individual, could be highly advantageous in such circumstances.
An example of an existing environment using changeable signs displaying route and target information is the so-called pick-to-light (PTL) system for warehouses. Such commercial systems and their advantages are described in the article "Pick-to-light directs productivity: however you store materials, PTL indicators make for timely and accurate orderpicking" by Schwind, Gene F., Material Handling Engineering, Dec. 1993, Page 43, downloaded through Compuserve Information Services. In such pick-to-light systems, the pick assignments are stored in a central computer. The central computer communicates with terminals positioned next to stock locations. When a certain pick assignment is activated by the central computer, lights in the corresponding terminals are turned on to provide the picker with clear visual guidance signals. Additional information may be generated by the central computer and displayed by the terminal, such as information relating to the pick quantity. The terminal may also include input means for keying-in and uploading pick reports. Other prior art references relating to pick-to-light systems include U.S. Pat. Nos. 3,739,339 to Hilihouse et al., 3,908,800 to Drapeau and 4,346,453 to Drapeau et al.
While having many advantages regarding productivity and accuracy, the existing pick-to-light systems have two major limitations: they can serve only a single picker or a small number of pickers operating simultaneously, and they require a costly communication infrastructure between the central computer and all terminals.